Self referencing (1:1) a table in Entity Framework code first model - entity-framework

Question

I'm trying to self reference a table in my model to get a couple of details for my User entity
I have a class that looks like:
public class User
{
[Key]
[Column("recid")]
public int Id { get; set; }
[Column("givenname")]
public string FirstName { get; set; }
[Column("sn")]
public string LastName { get; set; }
[Column("mail")]
public string Email { get; set; }
[Column("managerEmail")]
public string LineManagerEmail { get; set; }
public string LineManagerFirstName { get; set; }
public string LineManagerLastName { get; set; }
}
How can I map this so that when returning a User the LineManagerFirstName and LineManagerLastName is retrieved from the same table, joined on LineManagerEmail?
for example, I anticipate the SQL to be something like:
SELECT
user.recid,
user.givenName,
user.sn,
user.mail,
user.managerEmail,
manager.givenName as lineManagerFirstName,
manager.givenName as lineManagerLastName,
FROM user
INNER JOIN user AS manager
ON user.managerEmail = manager.mail
In my Context class, I know I'll need to override the OnModelCreating method:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().
}
...but being new to EF, this is where I'm getting a bit stuck!

Answer 1

If you use a view, you will probably not be able to update users as a view is readonly.
You should create entities according to tables and then query according to your needs and materialize a UserExtended with a query like
var q = from
u in Users
select
new UserExtended {
Id = u.Id,
/* .... */
LineManagerFirstName = u.Manager.FirstName
/* .... */
}
or a more elaborated query, in case of self join without the PK.
var q =
from u in Users
join m in Users on u.Email equals m.Email
select
new UserExtended {
Id = u.Id,
/* .... */
LineManagerFirstName = m.FirstName
/* .... */
}
will give you the following SQL (fields name do not match as I use one of my schema)
SELECT
[Extent1].[idUtilisateur] AS [idUtilisateur],
[Extent2].[Email] AS [Email]
FROM [dbo].[tableU] AS [Extent1]
INNER JOIN [dbo].[tableU] AS [Extent2] ON
([Extent1].[Email] = [Extent2].[Email])
OR (([Extent1].[Email] IS NULL) AND ([Extent2].[Email] IS NULL))